Pipe-vibration reducer

ABSTRACT

This invention relates to a pipe-vibration reducer device arranged to be fixedly mounted at any desired radial position about a pipe, so as to reduce abnormal or resonant pipe vibrations to acceptable levels by having its natural frequency tuned to the frequency of the vibrating pipe. The device includes a mounting bracket defined by first and second clamp members, a dynamic mass being supported in a pair of carriage members which are slidably supported by compression springs within guide-bar members secured to the first clamp member.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation-in-part of application Ser. No. 444,540 filedFeb. 3, 1983, which is being abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to a vibration reducer and/or dampenerdevice, and more particularly to a vibration reducer and dampener incombination with pipes used for gas or liquid.

2. Description of the Prior Art

Problems and difficulties are being encountered in providing suitablemeans for reducing and/or dampening vibrations along the longitudinallengths of strings of pipes.

Various types of vibrational dampening devices are known, but these aregenerally applied to transmission-line cables and like structures. Asexamples of these types of devices, one may refer to U.S. Pat. Nos.1,995,620; 2,132,319; 3,614,291 and 3,664,620.

U.S. Pat. No. 4,203,546 discloses an oscillation dampening system forrailway tracks.

The above-mentioned patents have features that restrict their use, andare generally not compatible with pipe structures associated with thepresent invention.

BRIEF SUMMARY OF THE INVENTION

The present invention has for an important object to provide apipe-vibration reducer and/or dampener that reduces abnormal or resonantpipe vibration to acceptable levels by having its natural frequencytuned to the frequency of the vibrating pipe. After the reducer is tunedto the pipe's vibration, the pipe will become essentially motionless.

It is an another object of the present invention to provide a vibrationreducer for liquid and gas pipe systems, wherein the reducer includes amounting bracket for attachment to a pipe, the bracket being arranged tosupport a floating mass by means of a pair of springs. Once the valuesof the mass and the spring members are determined, the reducer can bereadily tuned from vibration measurements, so as to provide thenecessary frequency-tuned, one-dimensional motion of the reducer withrespect to the pipe.

Still another object of the invention is to provide an apparatus of thischaracter that is arranged to be directly clamped to a pipe without anyother means of support, thus establishing a reducer that is essentiallysupportless with respect to the main supporting structures of the pipe.

It is still another object of the invention to provide a vibrationreducer for pipes wherein the dynamic mass is supported at its oppositeends by carriage members which are slidably mounted between support barsby means of anti-friction bearings, and held in place by spring memberswhich are interposed between the floating mass and the mounting bracket,so as to freely transmit vibration into the dynamic mass.

A further object of the invention is to provide a device of thischaracter that is readily tunable to the frequency of the vibratingpipe.

A still further object of the present invention is to provide a deviceof this character that establishes a nearly frictionless motion for thevibrating mass and spring combination.

It is still a further object of the invention to provide apipe-vibration reducer that includes relatively few operating parts, andis easy to service and maintain.

Still another object of the present invention is to provide apipe-vibration reducer that is relatively inexpensive to manufacture andcan be conveniently located on a string of pipes, thus eliminatingexpensive pipe-support devices for dynamic loads such as earthquakes,water-hammers and pump vibrations.

The characteristics and advantages of the invention are furthersufficiently referred to in connection with the accompanying drawings,which represent one embodiment. After considering this example, skilledpersons will understand that variations may be made without departingfrom the principles disclosed; and I contemplate the employment of anystructures, arrangements or modes of operation that are properly withinthe scope of the appended claims.

DESCRIPTION OF THE DRAWINGS

Referring more particularly to the accompanying drawings, which are forillustrative purposes only:

FIG. 1 is a side-elevational view of the present invention with portionsthereof broken away to illustrate various components of thepipe-vibration reducer as it is mounted to a typical pipe;

FIG. 2 is a cross-sectional view taken substantially along line 2--2 ofFIG. 1; and

FIG. 3 is a graphical representation of the vibrational frequencies.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 1 and 2, there is shown a pipe-vibration reducerdevice, generally indicated at 10, which is arranged so as to be fixedlymounted to a typical pipe 12. It should be noted first that the presentinvention is required to be adapted to correspond to the various pipediameters. Accordingly, the pipe-vibration reducer comprises a mountingmeans, designated at 14, which is defined by a pipe bracket formed by afirst longitudinal clamp member 16 and a second longitudinal clampmember 18. The first clamp member 16 includes a semicircular body havingside-extended flanges 20. The second clamp member 18 also includes asemicircular body having side-extended flanges 22. In order to mount thedevice to a pipe, the two clamp members 16 and 18 are positioned aboutpipe 12 and are clamped into a suitable fixed position by bolts 24,which are secured to flanges 20 and 22 as shown. It is important to notethat pipe-vibration reducer 10 may be positioned at any suitable radialangle, the preferred position being vertical, as shown.

Fixedly mounted to the first clamp member 16 is a means to guide thedynamic mass 30. Preferably, the guide means will be comprised of twogroups of three guide-bar members 26, each group being located adjacentthe opposite ends of first clamp member 16. Thus, the guide bars arearranged to slidably receive carriage members 28 defined as open-endboxes in which the opposite ends of the dynamic mass (preferably a steelbar) are secured and supported in the respective carriage members 28, asillustrated in FIG. 1. Mass 30 is secured to the carriage members bybolts 32.

The three guide bars 26 of each group are so positioned that there is anend bar 26a and oppositely disposed side bars 26b, so that therespective carriage members can freely oscillate longitudinally alongthe guide bars without restriction. This, in turn, allows mass 30 tooscillate so as to absorb the transferred vibration of pipe 12.

Moreover, in order to establish an anti-frictional, free-floatingmovement for carriages 28 and mass 30, there is provided a bearing means(generally indicated at 35) interposed between the walls 36 of carriagemembers 28 and guide bars 26. It is contemplated that various types ofbearing means may be suitably employed, but for illustrative purposesball bearings 38 are shown positioned within grooves 40 of bars 26 andgrooves 42 in carriage walls 36.

Interposed between the bottom of each carriage member 28 and the firstclamp member is a resilient support means defined by a pair ofcoil-compression springs 44. The upper end of each compression spring 44is secured to the underside of the respective carriage members 28. Asillustrated in FIGS. 1 and 2, one end of the spring is mounted to adepending boss member 46 formed on the bottom wall of each carriage 28,the opposite end thereof being attached to a second boss member 48formed on the first clamp member 16. The springs are affixed to eachboss member by pins 50. However, other fastening means may be used, suchas welding.

Since the springs 44 are interconnected to the carriages and their firstclamp member, the pipe-vibration reducer device may be mounted at anyradial position about pipe 12, as might be required.

Hence, the pipe-vibration reducer 10, when mounted to pipe 12, willreduce abnormal or resonanct pipe vibration to acceptable levels byhaving its natural frequency tuned to the frequency of the vibratingpipe. In order to accomplish the tuning of the frequency, one or moretuning plates or bars 45 (shown in phantom lines in FIG. 1) may bemounted to mass 30. After the device 10 is properly tuned to thecorresponding vibration of pipe 12, the pipe will become essentiallymotionless. Analytically, this is shown in FIG. 3.

The dimensionless deflection of a typical span of pipe M₁ is plottedagainst the ratio of the frequency of the vibrating-pipe span to thenatural frequency of the pipe-vibration reducer M₂. The dashed curves inFIG. 3 are actually negative values, which are conveniently shown aspositive values. Two typical resonance-deflection points for thetwo-dimensional dynamic system (pipe and vibration reducer) are shown atfrequency ratios of 0.82 and 1.16. Also, the zero-deflection point isshown for the pipe span at a frequency ratio of 1.0. The zero-deflectionpoint of the pipe span and the two resonance-deflection points for thepipe span and pipe-vibration reducer define the design requirements forthe pipe-vibration reducer.

The nature of the pipe-vibration reducer is the combination of the mass(steel bar 30) and the stiffness of the resilient means (springs 44).The values for the mass and the stiffness are precisely determined fromFIG. 3 or from vibration measurements, to provide the necessaryfrequency-tuned, one-dimensional motion of the pipe-vibration reducerwith respect to the pipe. The pipe-vibration reducer 10 clamps directlyto pipe 12 and requires no other means of support, which makes itessentially supportless with respect to the main supporting structuresof the pipe (not shown). Nearly frictionless motion is provided betweenthe mass 30 (steel bar) and its supporting structure by anti-frictionball bearings 38. This nearly frictionless motion is necessary to enablethe mass the springs to move freely. The mass must be precisely balancedto prevent the bar from rocking on the two springs.

In order to more effectively reduce transient pipe vibrations such asfrom earthquakes and water hammers, and also steady-state vibrations, acombination of two or more pipe-vibration reducers may be installed on asingle pipe or a piping system of headers and brackets. This increasedeffectiveness in reducing vibrations is achieved by tuning thepipe-vibration-reducer units to overlap resonance-frequency points ofone unit with the zero-deflection frequency point of another unit--thusachieving a frequency band of zero deflection instead of azero-deflection-frequency point, as shown in FIG. 3.

The invention and its attendant advantages will be understood from theforegoing description; and it will be apparent that various changes maybe made in the form, construction and arrangement of the parts of theinvention without departing from the spirit and scope thereof orsacrificing its material advantages, the arrangement hereinbeforedescribed being merely by way of example; and I do not wish to berestricted to the specific form shown or uses mentioned, except asdefined in the accompanying claims.

I claim:
 1. A frequency-tunable, vibration-reducer device for pipes andthe like, comprising:a mounting bracket defined by a first clamp memberand a second clamp member, means for securing said first and secondclamp members together wherein said clamp members are adapted to befixedly secured to a pipe at any desired radial position thereon; adynamic mass freely mounted to said first clamp member; guide meanssecured to and extending transversely of said first clamp member; a pairof carriage members slidably received in said guide means, andsupporting said dynamic mass within said guide means said entire dynamicmass being linearly moveable along with said carriage members indirections toward and away from said first clamp member; bearing meansinterposed between said carriage members and said guide means, wherebysaid dynamic mass may move freely without restriction; resilient meansinterposed between said carriage members and said first clamp member;and means for securing said resilient means to said carriage members andsaid first clamp member, whereby the resonant vibration of said pipe isdirectly transferred through said resilient means and into said dynamicmass, thus allowing said dynamic mass to be located radially outwardfrom said pipe at a selective angular position relative to said pipe. 2.A frequency-tunable, vibration-reducer device as recited in claim 1,wherein said guide means comprises:a first group of guide bars securedto one end of said first clamp member; and a second group of guide barssecured to the opposite end of said first clamp member, wherein each ofsaid groups of guide bars are arranged to slidably receive saidrespective carriage members therebetween.
 3. A vibration-reducer deviceas recited in claim 2, wherein said carriage members are each defined byan open-end box structure having an end wall and side walls, and abottom wall open at its top and on one side, so as to receive therespective ends of said dynamic mass; and wherein said ends of saiddynamic mass are attached to said respective carriage members.
 4. Avibration-reducer device as recited in claim 3, wherein each of saidguide-bar groups comprise three guide-bar members, one of said guidebars being positioned adjacent said end wall of said carriage and theremaining two guide bars being positioned adjacent said oppositelydisposed side walls of said carriage members.
 5. A vibration-reducerdevice as recited in claim 4, wherein said resilient means comprises apair of compression springs, each of said springs having one endattached to said bottom wall of said carriage, the opposite end beingattached to said first clamp member.
 6. A vibration-reducer device asrecited in claim 5, wherein each of said clamp members includes anelongated semicircular body member having laterally extended flangemembers, and fastening means adapted to be received in said flangemembers of said clamps.
 7. A vibration-reducer device as recited inclaim 4, wherein said dynamic mass is a metal bar.
 8. Avibration-reducer device as recited in claim 4, including means foradjustably tuning the resonant vibration of said dynamic mass withrespect to the frequency vibration of said pipe.
 9. A vibration-reducerdevice as recited in claim 8, wherein said adjustable tuning meanscomprises one or more tuning plates mounted to said dynamic mass.